The SDLP Deputy First Minister, Mr Seamus Mallon, has accused Mr Peter Mandelson of selectively quoting his party's views on the Policing Bill to US politicians.
Mr Mallon said the Northern Secretary had adopted "an a la carte approach" to SDLP opinions on the bill which is currently before the House of Lords. He was speaking after obtaining a copy of a letter Mr Mandelson sent to a US congressman.
In the letter to Congressman Richard Neal, of Massachusetts, which has been released to the press, Mr Mandelson quoted Mr Mallon as saying progress had been made and the British government "in response to SDLP concerns had agreed to bring some important matters back into line with Patten".
It also quoted Mr Eddie McGrady MP, of the SDLP, as saying "advances and further advances can be expected". Mr Mallon said that if the Northern Secretary wished to quote the SDLP on the Policing Bill, he should quote its views in full.
In the letter of July 7th, Mr Mandelson told Congressman Neal the British government was "totally determined" to secure a new beginning to policing and had remained faithful to the recommendations of the Patten Commission.
But he also noted that the report by the commission said "no individual, no commission, can claim omniscience and we do not contend that every recommendation in our report is correct in every particular".
The Northern Ireland Secretary said he recognised his Policing Bill needed to be "fine-tuned" and that genuine concerns had been expressed about its contents.
Therefore, significant changes had been made to the Bill including to the report and inquiry powers of the board scrutinising the new police service, to provisions on the code of ethics for officers, the oath and the 50-50 recruitment of Catholics and Protestants.
The letter continued: "The government will consider further constructive changes and amendments to the Bill as it progresses through parliament. It is worth noting that our approach has led to positive comments from political leaders from the nationalist community."
Mr Mallon said Mr Mandelson had ignored his party's "continued and profound concern at the failure to reflect Patten in other parts of the Bill". He also said: "To write to members of the US Congress relaying that with which the Secretary of State agrees and ignoring that with which the Secretary of State disagrees is selective and misleading."
The party had acknowledged what progress had been made in bringing the legislation back into line with the Patten recommendations. However, in its own letter to the US politicians, the SDLP also pointed out its "grave dissatisfaction on a range of cultural and structural issues".
Mr Mallon said: "Resolutions have been tabled in the US Senate and the House of Representatives calling on the British government to implement Patten in full. The SDLP is happy to support these helpful resolutions. They clearly show that Americans do not believe British claims that the Bill implements Patten properly."
The SDLP also released a letter from six US congressmen saying the Patten Commission's recommendations should be implemented comprehensively. The letter, signed by Democrats Mr Richard Neal, Mr Martin Meehan, Mr Joseph Crowley and Mr Sam Gejdenson, and by Republicans Mr Ben Gilman and Mr Peter King, said policing reforms were an essential part of the Belfast Agreement and a "touchstone issue" for nationalists.
A Northern Ireland Office spokesman insisted that Mr Mandelson had acknowledged the SDLP's qualms about the Policing Bill, saying: "Earlier this week Mr Mandelson acknowledged their concerns and said there had been over 60 amendments to the Bill, many of which reflect those concerns. The SDLP's concerns have been and are being addressed as the legislation goes through parliament."